44 



CEBEAL AND FORAGE INSECTS. 



which gave accurate data upon the time required for the various 

 stages in the life cycle. 



It is a matter of regret that this system was not discovered during 

 the work in Louisiana, only one similar method being employed. 

 This consisted in suspending a breeding cage from a small scaffold 

 over the growing head and artificially introducing the adult midges 

 from a bell jar. (See fig. 23.) 



In Louisiana great difficulty in these life-history studies arose from 

 the depredations of the Argentine ant (Iridomyrmex humilis Mayr). 



Fig. 23.— Breeding cage suspended over growing sorghum. Three sides of the 

 cage are covered with cheese cloth; the fourth is fitted with movable glass. 

 With this arrangement artificial breeding of the sorghum midge can be 

 observed under absolutely natural conditions. (Original.) 



These ants repeatedly gained access to breeding cages in the labora- 

 tory and destroyed the results by extracting the midge pupae from 

 the apex of the spikelet just prior to emergence, and also by capturing 

 the adults which had succeeded in emerging. 



HOST PLANTS. 



In addition to the many varieties of sweet sorghum, the sorghum 

 midge is known to infest broomcorn, kafir, Johnson grass, and milo. 



